Excerpted from Outdoor Navigation with GPS, 2nd edition, by Stephen W. Hinch, Wilderness Press, November 2007.
In the simplest sense, a GPS receiver measures your exact position anywhere on earth, but navigation in the wilderness involves much more than knowing where you are. Now is a good time to introduce what I call the Cardinal Rule of GPS Navigation: It doesn't do you any good to know where you are if you don't know where you want to go.
The real contribution of GPS isn't showing you where you are, but showing how to get where you want to go. The problem is complicated by the fact that GPS receivers report numerous other pieces of information besides your current position. How do you know what's important and what isn't?
First remember that all GPS receivers really only measure three things: your position, your speed, and the current time. (More expensive receivers sometimes include a true magnetic compass and barometric altimeter, but these are completely separate instruments that don't use GPS to make their measurements.) All the other features — things like distance, bearing, map location, and even such vital details as sunrise and sunset or the best fishing times — are just calculations your receiver makes from those three measurements. That's why even the least expensive units work fine for outdoor navigators. They might not offer a lot of extras, but they all do the few things you really want.
So what are those few things? For outdoor navigation, there are only four things you should really know how to do with your GPS receiver. If you can do these, you can successfully navigate in the wilderness. They are:
- Know how to store your current location in GPS memory. This is known as marking a waypoint.
- Know how to get back to that stored location from wherever you might be. You'll do this by the technique of following a bearing.
- Know how to program into your GPS receiver the coordinates of locations you want to go to. This is known as entering a waypoint.
- Know how to navigate from one stored waypoint to the next in succession until you get to your final destination. This is known as following a route.
It's as simple as that. If you know how to do those four things, you'll be able to get where you want to go and return safely. Most of the rest of this book shows you how to do them. It also discusses the important topic of what to do when your GPS receiver fails. And to keep all this knowledge from going to waste, it ends up with some fun things to do with GPS.
The Four Essential GPS Skills
- Store your current location as a GPS waypoint.
- Return to a stored waypoint by following a bearing.
- Program waypoint latitudes and longitudes into your GPS receiver.
- Navigate from one waypoint to the next in succession until you reach your final destination.
